What is Mechanical Seal(II)

IV: Normal Operation and Maintenance Issues of Mechanical Seals

  1. Preparation and Precautions Before Startup:

    • Comprehensive inspection of mechanical seals, auxiliary devices, and pipeline installations to ensure completeness and compliance with technical requirements.
    • Conduct a static pressure test before starting the mechanical seal to check for leaks. If there is significant leakage, identify and eliminate the cause. If ineffective, disassemble, inspect, and reinstall. Typically, the static pressure test pressure is 2-3 kg/cm².
    • Rotate the pump in the direction of the arrow and check for smooth operation. If there is resistance or it doesn't move, check for assembly errors or improper installation.
  2. Installation and Shutdown:

    • Ensure that the seal chamber is filled with liquid before startup. For conveying solidifying media, use steam to heat the sealing chamber to melt the substance. Before starting, rotate the disk to prevent sudden starts that could lead to the rupture of the soft ring.
    • For mechanical seals using an external oil system for the pump, start the oil system first. Stop the oil system last after shutdown.
    • After the hot oil pump is shut down, do not stop the cooling water for the oil chamber and end face seal immediately. Wait until the oil temperature at the end face seal drops below 80 degrees before stopping the cooling water to avoid damaging the seal components.
  3. Operation:

    • If there is a slight leakage after the pump starts, observe for a period. If the leakage does not decrease after continuous operation for 4 hours, stop the pump for inspection.
    • The operating pressure of the pump should be stable, with pressure fluctuations not exceeding 1 kg/cm².
    • Avoid cavitation during pump operation to prevent dry friction and seal damage.
    • Regularly check the seal condition. If the leakage exceeds the standard during operation (heavy oil not exceeding 5 drops/minute, light oil not exceeding 10 drops/minute), and there is no improvement within 2-3 days, stop the pump for inspection of the sealing device.

V: Structure and Maintenance of Mechanical Seals

  1. Structure:

    • The typical structure generally consists of a moving ring, stationary ring, moving ring seal ring, stationary ring seal ring, spring, spring seat, fastening screw, anti-rotation pin, etc.
  2. Principle:

    • During the operation of the mechanical seal, the axial force caused by the pressure of the sealed fluid and the elastic force of the elastic element makes the moving ring and the stationary ring fit and move relative to each other. The tight fit of the two sealing faces creates a tiny gap at the junction (seal interface). When the pressure medium passes through this gap, a very thin liquid film is formed, creating resistance that prevents medium leakage. Simultaneously, the liquid film lubricates the end face, ensuring long-term sealing effectiveness.
  3. Classification:

    • By the main host of the seal: Mechanical seals for pumps, kettles, compressors, etc.
    • Based on different working parameters: High temperature, medium temperature, low temperature, high pressure, medium pressure, low pressure, high speed, heavy-duty, etc.
    • According to the structural form: Balanced and unbalanced types, single and double end face mechanical seals, etc.
Back to blog

Contact Form